Failure means disaster for our planet. But does Blair begin to understand?

Whatever deal comes out of Jo'burg will not be enough. But failure to agree could sink hopes of international cooperation for years to come, writes Geoffrey Lean

Tomorrow Tony Blair will be flying into one of the greatest challenges of his premiership. The question is, does he realise it?

He should do. For as his deputy, John Prescott, told The Independent last week – and as many delegates here confirm – the whole multilateral system of international negotiations, developed over the past 50 years, is at stake at the Earth Summit. And Britain, and the Prime Minister personally, will play a pivotal role in deciding whether the summit succeeds or whether its failure leads the whole system to unravel.

Some senior figures in George Bush's administration do want to end the system of international negotiations that has built up a framework of agreements from the environment to human rights, from development to arms control – and helped to bring the world half a century of relative peace. They recoil from a system where the United States can (even if it rarely is) be outvoted by the rest of the world – and believe it stands in the way of its unilateral exercise of power.

But, to widespread surprise, their views are not evident here. Huge gaps remain between the United States and most of the rest of the world, but its delegates are negotiating constructively. There is an extraordinary, and unexpected, determination to reach agreement – because, as delegates freely admit, everyone is scared of the awesome consequences of failure. But that does not by any means guarantee that the summit will succeed.

After a week of negotiations here, officials have succeeded in clearing up a host of minor disagreements in a proposed plan of action and in making solid, if limited, progress on a few issues such as protecting fish stocks and controlling dangerous chemicals. But all the major disputes, covering almost everything of substance in the action plan, remain unresolved.

The big difference is between the US, and a few of its allies, who are determined to avoid making new commitments and setting new targets for achievement, and other countries – especially the European Union – who believe that any agreement will be meaningless without them.

Given time, the goodwill at the summit would probably be enough to bridge even this fundamental divide with hard but constructive bargaining. But time is quickly running out. The delegates are supposed to agree the plan of action – and a highly sensitive declaration of will – by tonight, ready for the leaders who start arriving tomorrow.

And reaching agreement at any cost will not do. That could result not merely in the world failing to move forward in tackling the escalating and interlinked environment, poverty, and security crises assailing the planet, but also in it actually going backwards. For the US is even resisting some of the principles which were agreed by heads of government (including Mr Bush's own father) at the Rio Earth Summit 10 years ago – including those endorsing the wisdom of taking precautionary action against serious environmental threats, and accepting that the richer countries (which have caused most of the problems) bear the heaviest responsibility for finding their solutions.

It would be nice to argue here for a really effective plan, something remotely commensurate with the scale of the threats facing the planet. But that would be a waste of printer's ink, for any chance of that vanished long ago. As a top negotiator put it to me: "The choice is between disaster and incremental improvement. Nothing terrific is on the table."

What, then, might an acceptable agreement contain? It is hard to see how it could carry credibility unless it included a target to cut by half the number of people (2.4 billion) without adequate sanitation by 2015. The world has already agreed to halve the number of people without safe drinking water by that date, and one cannot be achieved without the other.

The US will probably drop its opposition to that target, but that will not be enough. There will also need to be other targets, particularly on increasing renewable energy, maybe on reducing the loss of wildlife species, if any forward movement is to be made. And the world will have to show that it is willing to put a human face on globalisation, to make it serve people, not just capital.

It is a lot for the US to agree to, but it could well happen. No one – least of all Washington – wants to be blamed for the consequences of failure here. And at a string of previous negotiations over the past 12 months, the US has eventually gone further than anyone had expected. But time is short.

This is where Tony Blair – literally – comes in. He has a unique capacity to make a speech that resonates with the American people. He has, as we keep hearing, a unique relationship with President Bush that he could use to avert disaster. But has he the insight to see the importance of the moment, and the will to act? Tomorrow, one way or another, we will know.

The biggest problems: marks out of 10 so far

Water and sanitation

Nearly two and a half billion people lack adequate sanitation – one of the main causes of the waterborne diseases that kill 2.2 million people every year. Every country except the United States and Australia wants the summit to agree to halve this number by 2015. Even business agrees. The US is likely to give way, probably in exchange for getting its way elsewhere. As one US source put it: "The White House won't want to look as if it doesn't give shit."

Chances of success: 9/10

Energy

The other touchstone issue. Oil producing countries and the oil advocates in the White House have joined forces to sabotage any attempt to agree ambitious targets to increase the share of renewable energy – even though this would cut disease and combat global warming. Plans, produced at the request of the G8 leaders, to bring clean energy to a billion people by 2010, are buried. The best likely outcome is agreement on an EU proposal which would only increase the global share of renewables by 1 per cent this decade.

Chances of success 2/10

Agriculture

Some progress has been made on combating the desertification which is slowly turning one third of the world's land area to dust. The Global Environment Facility – the world's main provider of environmental aid – will in future be able to finance attempts to beat the problem, partly meeting the dire shortage of resources which has bedevilled the implementation of a treaty agreed after the Rio Earth Summit. But there is no sign of getting to grips with the thorny issue of EU and US agricultural subsidies.

Chances of success 4/10.

Biodiversity

The EU is insisting that the summit do something to tackle the fastest extinction of species since the death of the dinosaurs 65 million years ago. They want agreement on a target to "halt the alarming rate of loss" by 2010, and say they are prepared to bargain long and hard to get it. Everyone else opposes it, saying that the target is meaningless and will be impossible to achieve, even though the world agreed in only slighter weaker language at another conference earlier this year.

Chances of success 3/10.

Over consumption

The EU wants the summit to agree on a "10-year programme" to combat the over consumption in rich countries, which is one of the main forces behind environmental degradation. Under the programme, rich countries would have to report every year on what they were doing to reduce it. But the US is insisting that the programme should only be voluntary, which would allow it and other bad offenders to opt out. So far the Third World's position is unclear.

Chances of success 4/10.

Corporate accountability

This issue has largely been forced on to the agenda by pressure groups, who are making surprising progress with it. The EU has changed its position and now supports the groups' relatively modest demand for a study of the possibility of imposing rules of behaviour on multinational companies. They believe that the study could start a "snowball" rolling that would lead to regulation, and they are now working on developing countries to support the plan. The US and business are beginning to get concerned.

Chances of success 5/10.